The present invention relates to a scroll-type fluid machine that is usable as a compressor and a vacuum pump, and especially relates to a scroll-type fluid machine that is employed by, for example, a nitrogen concentrator or an oxygen concentrator for medical use.
In order for a gas such as nitrogen or oxygen contained in air to be concentrated at normal temperature, a membrane separation process, a PSA (Pressure Swing Adsorption) process using an adsorbent, or a process using an oxygen adsorbent (CMS; Carbon Molecular Sieve) is generally employed.
In the membrane separation process, air taken in from the atmosphere is pressurized by a compressor and sent to a hollow fiber membrane, and at the same time the hollow fiber membrane is evacuated using a vacuum pump provided on the exit side or part way along the hollow fiber membrane.
When the PSA process using an adsorbent is employed to concentrate oxygen using a nitrogen adsorbent (e.g., a zeolite), air taken in from the atmosphere is pressurized by a compressor and sent to an adsorption column, nitrogen is adsorbed from the air passing through the interior of the adsorption column, and the oxygen-enriched air so obtained is discharged from the exit of the adsorption column. When the adsorption of nitrogen by the interior of the adsorption column decreases, the passage between the upstream side of the adsorption column and the compressor is closed, the downstream side of the adsorption column is connected to a vacuum pump, and the interior of the adsorption column is evacuated by the vacuum pump so as to desorb the adsorbed nitrogen and return it to the atmosphere as an exhaust gas.
Furthermore, when the oxygen adsorbent (CMS) is used for oxygen concentration, air taken in from the atmosphere is pressurized by a compressor and sent to the interior of an adsorption column, and oxygen is adsorbed from the air passing through the interior of the adsorption column. The air from which oxygen has been removed is discharged from the exit of the adsorption column and returned to the atmosphere as an exhaust gas.
When the adsorption of oxygen by the interior of the adsorption column decreases, the passage between the upstream side of the adsorption column and the compressor is closed, the downstream side of the adsorption column is connected to a vacuum pump, and the interior of the adsorption column is evacuated by the vacuum pump so as to desorb the adsorbed oxygen and discharge oxygen-enriched air.
All of the above-mentioned processes require a compressor and a vacuum pump.
In the above-mentioned conventional techniques, since the compressor and the vacuum pump have to be provided separately, there are the problems that a large space is needed for the installation, the implementation in a confined space is difficult, the transport is inconvenient, and the transport cost increases.
In view of the above-mentioned disadvantages, it is an object of the present invention to provide a scroll-type fluid machine that can serve as both a compressor and a vacuum pump, can be used in a confined space, and is easily transported.
To achieve the object, in accordance with the present invention, there is provided a scroll-type fluid machine comprising:
a fixed scroll having a spiral-form fixed wrap on one side face;
an orbiting scroll having a spiral-form orbiting wrap on one side face facing the fixed scroll to form a sealed chamber between the fixed wrap and the orbiting wrap;
a drive shaft to which the orbiting scroll is connected to be able to revolve eccentrically with respect to the fixed shaft; and
an annular partition provided on either the fixed scroll or the orbiting scroll to separate the sealed chamber into an outer sealed chamber and an inner sealed chamber, said outer sealed chamber having an outer inlet on the outside and an outer outlet on the inside so that a gas taken in via the outer inlet may be compressed and discharged via the outer outlet, the inner sealed chamber having an inner inlet on the outside and an inner outlet in the inside so that a gas taken in via the inner inlet may be discharged via the inner outlet.
In accordance with the present invention, with a simple arrangement in which the outer sealed chamber and the inner sealed chamber are defined by the annular partition in the sealed chamber formed between the fixed scroll and the orbiting scroll, functions as both a compressor and vacuum pump can be imparted to the scroll-type fluid machine to reduce the size and weight, thereby achieving the cost reduction, enabling its use in a confined space, and making its transport easy.
Moreover, oxygen-enriched air can be obtained by one scroll-type fluid machine driven by a single drive source, without employing a compressor and a vacuum pump, by connecting the outer outlet of the scroll-type fluid machine to the entrance of an adsorption column and the inner inlet of the scroll-type fluid machine to the exit of the adsorption column.
Furthermore, allowing the inner sealed chamber to function as a vacuum pump can suppress any increase in the temperature of the central section of the scroll-type fluid machine, thereby extending the life span of grease and a bearing of an orbiting bearing arranged in the central section.